Although existing life span models suggest that positivity in relationships should benefit the health of older adults, much less is known about how relationships that contain both positive and negative aspects (i.e., ambivalent ties) might influence age-associated cardiovascular risk. Given the increased interpersonal stress associated with ambivalent ties, the SAVI model would predict that older adults might be more negatively influenced given age-related changes in physiological flexibility. In this study, the quality of an individual’s social network (i.e., supportive, ambivalent, aversive) was used to predict cardiovascular reactivity during laboratory stress across a 10-month follow-up period in 108 participants between the ages 30 to 70. Results revealed evidence that the number of ambivalent network ties predicted greater increases in diastolic blood pressure reactivity. Importantly, there was an Age × Ambivalent Ties interaction in which the number of ambivalent ties was related to greater increases in systolic blood pressure reactivity primarily in older adults. These data are discussed in terms of the health implications of social networks across the life span.